Conventional magnetorheological (MR) dampers include an MR damper having an annular cylinder, an MR piston, an MR piston rod, and an MR rod guide assembly. The annular cylinder has a top end and a bottom end. The MR piston is positioned in the cylinder, and the MR piston rod is attached to the MR piston and has one end extending outside the top end of the cylinder. The MR rod guide assembly includes a housing, two (primary and buffer) annular seals, an annular rod guide (also called a porous insert), a split bearing, and either an annular, plastic, piston-impact bumper or an annular, metallic piston-impact plate, depending on the application, wherein the bumper or plate, in addition to being designed to take up the impact from the piston at rebound, must also be designed to retain the buffer seal and to have added holes for flow to reach the porous insert.
The housing is attached to the cylinder at the top end and has a through bore. The two seals are positioned in the through bore and sealingly contact the MR piston rod. The rod guide is positioned in the through bore and is attached to the housing. The split bearing is positioned in and attached to the rod guide and contacts and slidingly receives the MR piston rod. The primary seal is self-attached and has a lip which is positioned in a seal gland of the housing. A seal retainer attached to the housing secures the buffer seal in the rod guide. The plastic piston-impact bumper is attached to the bottom of the housing.
The annular rod guide is a porous, powdered-metal rod guide which acts as a filter to filter out (e.g., iron) particles in the MR fluid to allow clear fluid to lubricate the MR piston rod as it slides into the bearing. The rod guide is made by expensive machining of a porous, powdered-metal right-circular cylinder to create the annulus including different diameter portions to accommodate the bearing and the buffer seal.
What is needed is an improved magnetorheological (MR) rod guide assembly and an MR damper having an improved MR rod guide assembly.